Mark Danner reviews two books and a documentary film about Donald Rumsfeld in the January 9 edition of the New York Review of Books.  He begins with Rumsfeld’s famous epistemological aphorism, which he has chosen for the title of his own book.

There are known knowns, the things we know we know. There are known unknowns, the things we know we don’t know. There are also that third category of unknown unknowns, the things we don’t know we don’t know. And you can only know more about those things by imagining what they might be.

To Rumsfeld, it is axiomatic that the attack on Pearl Harbor and those on New York and Washington six decades later have in common that they arose from “gaps in our knowledge, but gaps that we don’t know exist.” As he tells us bluntly in the author’s note that serves as overture to his enormous memoir:

Nineteen hijackers using commercial airliners as guided missiles to incinerate three thousand men, women, and children was perhaps the most horrific single unknown unknown America has experienced.

An engaging, even alluring idea and one that Rumsfeld is fond of linking to the analysis of the Harvard economist Thomas Schelling, who attributed, in a famous essay, the success of the Pearl Harbor attacks to a “poverty of expectations” on the part of American officials. “There is a tendency in our planning,” Schelling wrote in 1962, “to confuse the unfamiliar with the improbable.”²

But is this really what happened on September 11, 2001? Throughout that fateful summer, across the reaches of the country’s vast intelligence universe, “the system,” as Director of Central Intelligence George Tenet put it, “was blinking red,” and Tenet himself was said to be running about with his “hair on fire.” Meantime, the counterterrorism chief, Richard Clarke, newly demoted from Cabinet level, desperately struggled, as he had since January, to persuade his superiors in the new Bush administration to schedule a “Principal’s Meeting” on al-Qaeda. Panicked, he finally took to shouting angrily in meetings and e-mailing the national security adviser warning of “hundreds of dead in the streets.” He finally got his meeting—on September 4, 2001, a week before the attacks. But that was a month after the president had received this:

Bin Ladin Determined To Strike in US

Clandestine, foreign government, and media reports indicate Bin Ladin since 1997 has wanted to conduct terrorist attacks in the US. Bin Ladin implied in US television interviews in 1997 and 1998 that his followers would follow the example of World Trade Center bomber Ramzi Yousef and “bring the fighting to America.”

After US missile strikes on his base in Afghanistan in 1998, Bin Ladin told followers he wanted to retaliate in Washington….

An Egyptian Islamic Jihad (EIJ) operative told an [redacted] service at the same time that Bin Ladin was planning to exploit the operative’s access to the US to mount a terrorist strike….

Convicted [millennium] plotter Ahmed Ressam has told the FBI that he conceived the idea to attack Los Angeles International Airport [in 1999] himself, but that…Ladin lieutenant Abu Zubaydah encouraged him and helped facilitate the operation. Ressam also said that in 1998 Abu Zubaydah was planning his own US attack….

We have not been able to corroborate some of the more sensational threat reporting, such as that from a [redacted] service in 1998 saying that Bin Ladin wanted to hijack a US aircraft….

Nevertheless, FBI information since that time indicates patterns of suspicious activity in this country consistent with preparations for hijackings or other types of attacks, including recent surveillance of federal buildings in New York….³

This notorious document is not some random intelligence report that was floating around the bureaucracy and brought out after the fact. It is a Presidential Daily Brief, which means it is “finished intelligence” of the highest priority—thought vital enough to be read directly to the president of the United States at his vacation home in Crawford, Texas, on August 6, 2001. It was also distributed to senior national security officials of the US government, including Secretary of Defense Donald H. Rumsfeld.

Danner goes on:

Did the September 11 attacks truly arise from “gaps in our knowledge, but gaps that we don’t know exist”? To use Rumsfeld’s parlance, we knew what we knew: that terrorist attacks “in the US” were likely being planned, that they might well involve hijackings and target federal buildings. And we knew what we didn’t know: precisely when the attacks might be carried out, what the targets would be, how they would be attacked—though in truth even here there were clues, among them al-Qaeda’s obsession with the World Trade Center (the 1993 attack is mentioned in the Presidential Daily Brief) and an Islamic terrorist group’s earlier hijacking of a commercial airliner and its failed attempt to fly it into the Eiffel Tower.

What exactly were those “gaps that we didn’t know existed” that made the September 11 attacks, in Rumsfeld’s words, “the most horrific single unknown unknown America has experienced”? Was the failure to stop the attacks truly a failure of the imagination or was it a failure, as Morris says, to look at the intelligence that was available? And if it was the latter—a failure by senior leaders to look at and take seriously enough and act upon what was actually known—then the success of the attacks stemmed not from some universal human “failure of the imagination” or “poverty of expectations” but from the arrogance and willfulness of certain people to whom the country had entrusted the highest responsibility.

It will be hard to stomach the man Errol Morris shows us in his documentary, but necessary.  Meanwhile, beg borrow or use the library to read ALL of Danner’s article.